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Home » Calculate the mean of the following distribution using step deviation method:
Calculate the mean of the following distribution using step deviation method:
CBSE | Class 10 | Exercise 1 | Maths | Measures of Central Tendency | ML Aggarwal
Calculate the mean of the following distribution using step deviation method:
Marks 0-10 10-20 20-30 30-40 40-50 50-60
No. of students 10 9 25 30 16 10

Solution:

Class mark (xi) = (upper limit + lower limit)/2

Let assumed mean (A) = 25

Class size (h) = 10

Class Interval No. of students (fi) Class mark (xi) di = xi – A ui = di/h fiui
0-10 10 5 -20 -2 -20
10-20 9 15 -10 -1 -9
20-30 25 25 0 0 0
30-40 30 35 10 1 30
40-50 16 45 20 2 32
50-60 10 55 30 3 30
Total ∑fi = 100 ∑fiui =63

By step deviation method, Mean = x̄ = A+h∑fiui /∑fi

 = 25+10(63/100)

= 25+10×0.63

= 25+6.3

=31.3

Hence the mean of the distribution is 31.3.

i

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